Acc to a new study, over 1/3rd of the world's 246 longest rivers remain free-flowing. Dams & reservoirs are drastically reducing the diverse benefits that healthy rivers provide to people. Researchers found that only 21 out of 91 rivers longer than 1000km that originally flowed to the ocean still retain a direct connection from a source to sea. Untouched rivers are largely confined to remote places such as Arctic & Amazon.